Received August 10, 2018; Revised August 22, 2018; Accepted September 19, 2018.

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Abstract

Transient myeloproliferative disorder (TMD) is similar to congenital leukemia, with leukocytosis, increased peripheral blast cells, and hepatomegaly in the neonatal period. Although TMD occurs only in patients with Down syndrome and trisomy 21 mosaicism, there have been reports of congenital leukemia with trisomy 21 limited to hematopoietic cells showing spontaneous resolution. We identified trisomy 21 in the leukemic cells in a patient with congenital leukemia. As there was no other gene abnormality, we stopped chemotherapy, and the disease resolved spontaneously. We reviewed the cases of clonal trisomy 21 TMD and found that their clinical features were similar to those of TDM associated with Down syndrome. In conclusion, in a phenotypically normal patient with suspected congenital leukemia, it is necessary to confirm the presence of 21 trisomy. If the neonate has only trisomy 21 without other gene abnormalities, intensive chemotherapy may not be required.